Compact and easy to use, rareESSENCE Aromatherapy UltraSonic Diffuser. It's compact and portable. It plugs into a USB port or a wall outlet with an AC Adapter. Add 100ml of water and 2-10 drops of our rareESSENCE essential oils for a blissful aromatherapy experience. One button operation with auto-shutoff and multi-color light function. Great with sleep or relax oil in the evening , or Breathe easy for congestion.